Method of making printed sheet material



July 12, 195 J. N. MASON METHOD OF MAKING PRINTED SHEET MATERIAL Filed March 15, 1954 INVENTOR. JAMES N. MASON ATTORNEYS United States atent Patented! July 32, 1955 METHOD 3F IVIAKQJG PPENTED SHEET hiATERlAL Claims. (Ci. 4 -19 assignor to Boston Cambridge, lviass.,

The present invention relates to decorative sheet materials of rubber, or similar organic plastic materials, having printed surface designs, and provides a novel process of providing such materials with surface designs of soft or subdued texture.

Ordinary printing processes suitable for applying surface decoration to sheets of rubber or similar material result in patterns of sharp detail occasioned by the application of the ink in well defined areas. A more pleasing effect is achieved if the design is toned down to soften its texture by decreasing the contrast within the design and between the design and the background, but articles so decorated are generally the product of skilled handiwork or expensive and elaborate printing techniques hardly suitable for decorating rubber sheets.

According to this invention, a process is provided for treating rubber sheet materials or the like by ordinary printing techniques, e. g. block printing, silk screen printing or other techniques well known to the art, then moderating the colors and contrast between them and eliminating the sharp outlines within the design to soften the design and .in general give it a much more pleasing effect. If desired, designs produced according to this invention may in addition be given a mosaic eiiect characterized by discrete color specks of random shape generally defining a definite design. The invention accordingly utilizes conventional commercial printing techniques to produce on rubber and similar materials designs simulating the Work of skilled artisans.

In general, the invention is practiced by first printing the desired design on the surface of the sheet, then stretching the sheet in one or both directions, and finally permanently setting the sheet in its stretched condition. By this procedure, the sharp pattern or design initially printed on the sheet is distorted and thinned with the effect of blurring sharp outlines, establishing gradations between colors, and moderating the colors. If the stretching of the sheet is continued beyond the tensile limit of the in, the design achieves an attractive mosaic effect from fragmentation of the ink into discrete specks generally defining the initial design. In either case, sharp details are minimized and the texture of the pattern is greatly softened or subdued.

Sheet materials useful in the practice of this invention include in general, natural and synthetic rubber and other common plastic materials which may be stretched and then set in stretched condition, for instance, plasticized polyvinyl chloride, vinyl chloride-vinyl acetate copolymers, polyethylene, polyvinylidene chloride, vinyl chloride-vinylidene chloride copolymers, polyvinyl butyral, polyisobutylene, polystyrene, acrylic resins and plastic thermosetting resins, to name but a few.

The ink of which the design or pattern printed on the surface of the sheet is formed will, of course, depend to a large extent on the nature of the sheet and on the conditions of the processing to which it is subjected. In general, suitable inks comprise a pigment dispersed in a vehicle which is compatible with the sheet to which it is applied, and which is stable under the conditions to which it is to be subjected. Any of a number of the many difierent types of vehicles are satisfactory, including those formed of a drying oil as Well as varnish compositions containing in addition to drying oil, a natural or synthetic resin, and also vehicles comprising solutions of film-forming resins, or plastisol compositions comprising a finely-divided resin dispersed in a liquid plasticizer therefor. Hardening of the ink may be effected simply by permitting the ink to dry as by evaporation of solvent or by oxidation of a drying oil, or by applying heat or steam to effect activation of a plastisol vehicle or coagulation of the vehicles. In any case, however, an ink of good compatibility with the sheet should be used.

If a mosaic efiect occasioned by stretching the sheet to cause fragmentation of the pattern is desired, the ink should preferably be formed of a vehicle having limited elasticity when hardened so that the sheet may easily be stretched beyond the tensile limit of the ink.

In a typical embodnnent of this invention the facing ply of a sheet comprising a white rubber facing ply and a backing ply was first printed with a surface design in a standard commercial rubber printing ink. Each of the plies was formed by milling together the following ingredients according to standard rubber compounding procedure, and calendering the respective mixtures into sheets.

Facing ply stock Parts by weight Natural rubber 43.00 Zinc oxide 2.15 Titanium dioxide 25.87 Calcene 25.87 Benzothiazyl disulfide .35 Diphenylguanidine phthalate .11 Stearic acid .43 Di-beta-naphthyl-para-phenylene diamine .43 Carbon black .09 Ultramarine blue .20 Parafin wax .42 Sulfur 1.08

Backing ply stock Parts by weight GR-S Whole tire reclaim Zinc oxide Whiting Stearic acid .44 Parafin wax .88 Benzothiazyl disulfide .44 Diphenyl guanidine phthalate .13 Di-beta-naphthyl-para-phenylene diamine .44 Sulfur 1.10

After printing the facing ply, the ink was allowed to dry and the sheet in combination with the backing ply was stretched to elongate it by at least 5%, and While held stretched was pressed between two platens heated to vulcanization temperature.

In another embodiment, final pressing to vulcanize n e sheet in stretched condition was carried out with the printed surface in contact with a platen haviu sharp surface corrugations. In pressing the sheet against this platen a corrugated surface was formed on the material causing further stretching of the printed surface, and providing in addition a non-slip cushioned surface on the sheet.

In this connection, an advantage or" this invention has possible to obtain these desirable decorative etfects and at the same time provide an embossed surface to obtain been found to V non-slip characteristics or a cushioning effect A further step which may advantageously be included in the process of this invention is the applicatin of a lacquer to the printed surface after the ink has dried, and prior to stretching and vulcanization; This procedure provides a protective coating, lessening wear of the surface.

The degree of stretch required for purposes of this invention depends largely on the degree the printed pattern or design is to be subdued. in general, however, the printed sheet should be elongated at least 5%, preferably between about 5 and 30%, and frequently stretching by as much as MIG-150% is highly desirable. Where a mosaic effect is desired, stretching must be beyond the tensile lirnitof'the ink to cause fragmentation thereof, and this, of course, depends largely on the composition of the ink.

Stretching may, of course, be performed manually, followed by a'separate vulcanization step. in commercial production, however, it has been found highly advantageous to utilize apparatus designed to stretch the stock and volcanics it in stretched condition. Such apparatus is described in U. S. Reissue Patent No. 19,660. Other suitable apparatus for stretching the sheet is a tentering machine, with vulcanization performed in standard sheet vulcanizing machines suitable for holding the sheet against shrinkage during vulcanization.

in carrying out this invention using sheet materials other than rubber, the setting of the sheet in its stretched condition will require a somewhat With thermoplastic elastoineric materials, the setting of the sheet may be accomplished by heating'it to relieve internal stresses and thereby prevent elastic recovery. Materials such as vinyl resins, polyethylene, and vulcanized natural or synthetic rubbers may be so treated. The thermoplastic materials having little elasticity such as polystyrene or the arcylic resins may the other hand, be heated prior to stretching, to render them plastic, then strcthed and cooled to set them in stretched condition. in practicing the invention with elastic or plastic thermosetting resins as the sheet material, the stretched sheet may be heated in the presence of a polymerization catalyst to efifect final polymerization setting the sheet in its stretched condition. Accoi ingly, although the preferred embodiment is described with reference to rubber,'it will be understood that other stretchable materials may also be used with e 'ely satisfactory results.

further be appreciated that, in addition to providing sheets haying printed surface designs of subdued texture, the stretching operation increases the area yield of the printing process. Sheets of the minimum thickness for the printing process are reduced in thickness by the stretching while retaining the essence of the printed design, thus providing printed sheets thinner than have heretofore beenpractical.

This invention has been found particularly useful in the production or floor coverings such as corrugated rub- I for stair treads corrugated rubber runners A convenient method of forming such it will .lngs consists in printing the desired design in standard cornmer: al rubber printing ink on a calendered stock such as that described above. fa g ply i n fed simultaneously with a calentl sheet of backing ply stock, such as that disclosed above, into rotary vulcanizing machine (such as that described U. 8. Patent No. 2,039,271) with the printed surface of the facing ply in contact with the sheet of facin a different treatment.

. l heated rotating drum of the vulcanizing machine. The drum is usually formed with sharp parallel V-shaped corrugations running around its periphery against which the two plies of stock are pressed during vulcanization to form corresponding V-shaped corrugations at the printed surface or" the product. The printed facing ply is stretched prior to vulcanization in the direction it is fed into the vulcanizing machine by feeding it into the machine under a restraining tension, for instance by from a roll held against free rotation by no ns, or by means of tensioning apparatus such as that disclosed in U. S. Patent No. 2,082,895. Preferably, the sheet is elongated from 5% to 30% in this manner. The backing ply stock may be similarly elongated but this is not essential for the purposes of this invention.

'By providing corrugations or other embossed patterns on the periphery of the vulcanizing drum, the printed surface of the facing ply is subjected to stretching by as much as 158% in the direction perpendicular to that which it Was stretched during the feeding of the facing ply into the vulcanizing machine. The printed surface is thus stretched in two perpendicular directions, each to tae estent of between about 5% and 150% with the result that the printed attractiveness and serves extremely well to conceal the corrugations.

An idea of the effect of subjecting a printed sheet to stretching and setting in the stretched condition is shown in the drawings in which:

Fig. 1 shows a sheet having a surface design printed thereon, before stretching, and

Fig. 2 shows the same sheet after it has been stretched in accordance with this invention.

From Fig. l it will be seen that the original printed design tends to stand out boldly and in sharp contrast with the background. After the sheet has been stretched,

however, as shown in Fig. 2, the design is subdued and the contrast diminished giving effect.

Having thus disclosed my invention and described in detail preferred embodiments thereof, I claim and desire to secure by Letters Patent:

1. The method of producing a sheet having a printed surface design comprising applying printing ink to a surface of a sheet in a predetermined design, stretching said sheet in a direction parallel to its plane to elongate it by at least 5% in at least one dimension, and setting said sheet in its stretched condition.

2. The method of producing a sheet having a printed surface design comprising applying printing ink to a surface of a sheet in a predetermined design, causing the ink to harden, stretching said sheet in a direction parallel to its plane to enlongate it by at least 5% in at least one dimension, and setting said tion.

3. The method defined by claim 2 wherein the sheet is stretched beyond the tensile limit of the ink to produce a mosaic effect in the design.

4. The rnethod defined by claim 2 wherein the sheet is stretched to elongate it by between 5 and 159% in at least one dimension. 7

5. The method of producing sheet rubber having a printed surface design comprising applying printing ink to a surface of a sheet of unvulcanized rubber, stretching the 7 applying printing ink to a. surface of the sheet, stretching the sheet in a direction parallel to its plane to elongate it by at least 5% in at least one dimension, and heating said sheet to relieve the stresses therein and set it in its stretched condition.

design is greatly enhanced in its' a toned-down or softened sheet in its stretched condi-' 7. The method of producing a sheet of thermoplastic stretched condition.

8. The method of producing a sheet of an organic film-forming material having an embossed printed surface design comprising applying printing ink to a surface of the sheet in a predetermined design, stretching the sheet in a direction parallel to its plane to elongate it by at least in at least one dimension, embossing the printed surface of the sheet to stretch the surface further, and setting the sheet in its stretched condition.

9. The method of producing a sheet having a printed surface design comprising applying printing ink to a surface of a sheet in a predetermined design, stretching said sheet in a direction parallel to its plane to elongate it by at least 5% in at least one dimension, applying a coating of lacquer to the printed surface and setting said sheet in its stretched condition.

10. The method of producing a sheet of an organic film-forming material having an embossed printed surface design comprising applying printing ink to a surface of the sheet in a predetermined design, stretching the sheet in a direction parallel to its plane to elongate it by at least 5% in at least one dimension, applying a coating of lacquer to the printed surface, embossing the printed surface of the sheet to stretch the surface further, and setting the sheet in its stretched condition.

11. The method of producing sheet rubber having a printed surface design comprising applying printing ink to a surface of a sheet of unvulcanized rubber, stretching the sheet in a direction parallel to its plane to elongate it by at least 5% in two perpendicular dimensions, and vulcanizing the sheet in its stretched condition.

12. The method of producing sheet rubber having a printed surface design comprising applying printing ink to a surface of a sheet of corrugations running parallel to the direction of stretch thereby further stretching the sheet in the perpendicular direction.

13. A sheet comprising a stretchable material having a printed surface design, stretched by at least 5% in a direction parallel to its plane and permanently set in its stretched condition.

14. A sheet comprising rubber facing printed surface design stretched by at least tion parallel to its plane and vulcanized condition.

15. A sheet material comprising a rubber ply having a printed surface design, said ply having been stretched by between 5 and per its plane, embossed with parallel V-shaped corrugations ply having a 5% in a direcin its stretched References Cited in the file of this patent UNITED STATES PATENTS 

